Originally Posted by
Spoonrobot
He's not wrong, possibly something lost in translation. I've seen a few drive-trains that work fine - not skipping, shift ok (but clunky) - that will start skipping once the chain is cleaned and lubed. Well traveled shop hand passed this info onto me my first week on the job and it's saved me from an irate customer a few times.
Ex: Guy comes in for a drivetrain clean and adjustment ($) with a really gunked up cassette and chain (old WD-40 or 3-in-1), Chain shows 12 & 3/16" so I recommend replacement of cassette and chain ($$). He goes instantly to 100, takes his bike off the stand and tells me he's going to our brand X competitor ("you're trying to rip me off!"). Comes back the next weekend with a nice shiny drivetrain (same parts but clean) and tells my co-worker how the other shop messed up his bike, it's skipping under even moderate load. New chain and cassette solves the issue.
So in short, cleaning an already-way-too-elongated chain can make it skip, right. Alternate interpretation - enough gunk on an already-way-too-elongated chain can mask the fact that it's way too elongated. I can just imagine how hard that can be to explain to an "average" customer.
Still, that's a much better explanation than claiming that cleaning the chain MAKES it longer, as the OP was told. In short - if cleaning a chain makes it skip, it was probably shot in the first place. That would have been a more meaningful explanation than the "man-splanation" the OP got. Goes right back to why it's handy either to have a chain checker, or to measure it yourself, so you go into the shop already informed.